Science. The fate of the world’s largest ice sheet is still in our hands – Publimetro México

Madrid, 10 (European press)

A new study led by Durham University (UK) shows that the worst effects of global warming on the East Antarctic Ice Sheet (EAIS) could be avoided if temperatures rose no more than 2°C above pre-industrial levels.

If kept below this limit, the researchers say, the East Antarctic ice sheet, which contains most of Earth’s glacial ice, would contribute less than half a meter to global sea level rise. 2500. However, they add, if warming continues to increase beyond the 2°C limit, we can see EAIS contribute several meters to sea level rise in just a few centuries.

The research team, which includes scientists from the United Kingdom, Australia, France and the United States and whose findings are published in the journal Nature, studied the response of the ice sheet to past warm periods and examined the changes that are currently being produced.

They then analyzed a series of computer simulations from previous studies examining the effects of different greenhouse gas emission levels and temperatures on the ice sheet of the years 2100, 2300 and 2500.

Lead author, Professor Chris Stokes, from the Department of Geography, University of Durham, UK, said: “The main conclusion of our analysis is that the fate of the East Antarctic ice sheet is still in our hands. This ice sheet is the largest ever on the planet, which contains what It’s equivalent to 52 meters from sea level, and it’s really important that we don’t wake up this sleeping giant.”

“We used to think that East Antarctica was less likely to be affected by climate change, compared to West Antarctica or the Greenland ice sheets, but we now know that there are some areas in East Antarctica that are already showing signs of ice loss -” satellite observations have revealed signs of thinning and receding, especially when the glaciers draining the main ice sheet come into contact with warm ocean currents.”

The team’s analysis shows that if warming continues beyond 2100, due to high emissions, East Antarctica could add several meters to sea level rise over the next few centuries. This would add to the significant contributions of Greenland and West Antarctica and would threaten the millions of people around the world who live in coastal areas.

Professor Stokes adds that “restricting global temperature rise to below 2°C set by the Paris climate agreement should mean we avoid worst-case scenarios, or perhaps even stop the Earth’s ice sheet from melting.” Impact on global sea level rise”.

When world leaders gathered at the 2015 United Nations Climate Change Conference in Paris, they agreed to limit global warming to below 2°C and continue efforts to limit the increase to 1.5°C.

According to the latest report from the Intergovernmental Panel on Climate Change (IPCC), published last year, human activity has already increased the average global temperature by about 1.1°C since pre-industrial periods.

The study led by Durham showed that with a sharp decrease in greenhouse gas emissions and a slight increase in temperature, EAIS could contribute about 2 cm to sea level rise by 2100, which is much less than the ice loss projected in Greenland and West Antarctica. In fact, some research shows that snowfall has increased in East Antarctica in recent decades, and if this continues, it will offset some of the ice loss projected in the next century.

Alternatively, if the world continues down a path of very high greenhouse gas emissions, the researchers cannot rule out the possibility that EAIS will contribute about half a meter to sea level by 2100, but they consider it highly unlikely. If emissions remain high after 2100, EAIS could contribute to a sea level rise of one to three meters by 2300 and two to five meters by the year 2500.

More importantly, they point out, if the goal of the Paris Agreement is met, ice loss in East Antarctica could be significantly reduced or even avoided, and the EAIS contribution to sea level rise would still be less than half a meter by the year 2500.

The researchers also looked at the ice sheet’s response to warm periods in the past, when carbon dioxide concentrations and atmospheric temperatures were only slightly higher than today.

They claim that unlike the rapid and extreme warming we have seen in recent decades, which can only be explained by greenhouse gas emissions from human activity, the previous warming has occurred over long periods of time. For a much longer period it was largely caused by changes in the way the Earth revolves around the Sun.

For example, the last time carbon dioxide concentrations exceeded the current value of 417 parts per million was during a period known as the mid-Pliocene, about three million years ago. Temperatures were 2-4 degrees Celsius higher than they were then – within the range of temperature changes we might see by the end of this century – but global mean sea level was 10 to 25 meters higher.

Alarmingly, they add, evidence from seafloor sediments around East Antarctica indicates that part of the ice sheet collapsed and contributed to sea level rise during the mid-Pliocene. Even 400,000 years ago, not so long ago on geological time scales, there is evidence that part of EAIS retreated 700 km inland in response to global warming only 1-2°C.

Professor Nerely Abram, co-author of the study from the Australian National University in Canberra, stresses that “the main lesson from the past is that the East Antarctic ice sheet is very sensitive to even relatively modest warming scenarios. It is not that stable.” Nor is it as protected as we were. Believe. We now have a very small opportunity to rapidly reduce greenhouse gas emissions, limit the rise in global temperatures and preserve the East Antarctic ice sheet.”

Taking these steps will not only protect the East Antarctic ice sheet, but also slow the melting of other major ice sheets, such as Greenland and West Antarctica, which are more vulnerable and more vulnerable. Therefore, it is critical that countries meet to strengthen their commitments to the Paris Agreement.”